American Express credit card number validation
Q
All credit card numbers issued by American Express must start with 34 or 37 and have 15 digits. For example, 346997719493686 is a valid American Express credit card number.
How to write a single regular expression to validate a American Express credit card number described above?
✍: FYIcenter.com
A
Here is the regular expression for American Express credit card number validation:
^3[47][0-9]{13}$
^ - begin of the string
3[47] - matches 34 or 37
[0-9] - any decimal digit
{13} - repeating 13 times
$ - end of the string
2013-01-22, 4359👍, 0💬